1. Field of the Invention
This invention relates to a display apparatus for a vehicle, and more particularly to a display apparatus for a vehicle wherein a display image of a display device for displaying driving information such as a speed of a vehicle thereon is reflected in a field of view of a windshield toward a driver's seat side thereby to provide such driving information to a driver by way of an indication of a virtual image.
2. Description of the Prior Art
A display apparatus for a vehicle of the type mentioned normally employs, as a display element, a light emitting display device which provides an indication by emission of light such as a fluorescent display tube (VFT), a light emitting diode (LED) or a backlighted liquid crystal display element (LCD).
An exemplary one of such conventional display apparatus is shown in FIG. 13. Referring to FIG. 13, the conventional display apparatus shown includes a display device 61 for displaying a speed of a vehicle or the like thereon. The display device 61 is disposed on a dashboard 62 adjacent a windshield 63 of a vehicle in which the display apparatus is incorporated. Paint of a dark color such as black is applied to a portion of the windshield 63 adjacent a boundary between the windshield 63 and the dashboard 62 to form a reflecting portion 63a. Thus, a display image of the display device 61 is reflected toward a driver's seat side of the vehicle at the position of the reflecting portion 63a on an inner face of the windshield 63.
With the display apparatus, a display image of the display device 61 appears in a field of view of the windshield 63 on the background of the dark color of the reflecting portion 63a. Thus, the display apparatus forms a so-called head up display apparatus with which a driver of the vehicle can visually observe the display image without the necessity of moving its eyes very much during driving. Further, since the background of a display image looks dark, there is an advantage that a high contrast is achieved with a display image. It is to be noted that the reflecting portion 63a may be formed, for example, such that a ceramic coating 64 of black or the like is applied to the windshield 63 as shown in FIG. 14 or an opaque film 64' of black or the like is held between two layers of a glass laminate of the windshield 63 as shown in FIG. 15.
With the display apparatus, however, in the daytime when the circumference is bright, the visual observability is low if it is not caused to provide a display image with a high brightness sufficient to be superior to the brightness of the circumference. On the other hand, at night when the circumference is dark, such high brightness for the daytime will make a display image excessively bright and make it difficult to observe the display image.
Accordingly, a conventional display apparatus of the type mentioned often additionally includes a dimming circuit for changing over the brightness of a display image itself of a display device in the daytime and at night. Such additional provision of a dimming circuit, however, makes the display apparatus complicated and requires an increased number of working steps for production and adjustment of such dimming circuit, which results in increase in cost of the entire display apparatus.
The conventional display apparatus has another problem that, since the dark reflecting portion 63a looks on the windshield 63 from the outside of the vehicle, the appearance design of the vehicle is deteriorated thereby. Besides, since the reflecting portion 63a is formed on the windshield 63, the manufacturing procedure thereof is restricted and an operation for the maintenance is elaborate.